[city-dweller]

Personally, I don't see why the engraving should be removed.

After all, the original watch did have it (Knirim, p. 450):

(I already posted this image two weeks ago
https://www.watchuseek.com/f440/201...ect-theme-527732-post3884272.html#post3884272 )

 

[city-dweller]

On the pic, what kind of surface does it seem to have? Looks brushed on my screen.

here is what I found in Knirim:
the watch shown in the picture apparently belongs to the first production (prototype?) series,
which featured silver (bead-blasted?) cases.

the case is quite worn, and therefore looks rather smooth on the photo.
a closer look shows a grainy surface structure -- therefore I would assume
it was originally bead-blasted.

in the later series (starting March 1941, 10 watches per month),
cases were made of nickel-plated brass.

 

[city-dweller]

City-dweller, any possibility to loosly and quickly translate the text?

Janne, the document shown in the image
is a letter from A. Lange & Sönne,
which is a part of their correspondence regarding
the design of this watch.

Here is a quick translation:

===============================================
August 26, 1940

To:
Office of Armaments and Devices of the Troops SS
Berlin-Wilmersdorf

Re:
Your previous letter of 19.8.40
Az. Artl. Az. 422/B 9/40 Sch/St.
Observer's watch for the measurement battery with
a balance stopping device

Concerning the development of a dial, which can be photographically captured using
artificial lighting in day and night conditions, we notice that your design "a" appears
to be the best legible one. We believe the version with a matte black dial to be most
appropriate. Making the dial surface matte would prevent reflexes in the photographic
reproduction of the dial. The minute and hour digits can be made using a luminous
material. On the other hand, it is practically impossible to make either the 1/5-second,
or second, or 5-second ticks luminescent; the latter two, at least not as far as
they extend into the 1/5-second scale, because of lack of space to make an exact
1/5-second scale. The luminous material requires too much space for that.

Because of this, the 5 -, 1 - and 1/5-second ticks will be made simply white in color
(non-luminescent). The large second hand will be luminous by about 80 to 90 percent,
and the tip of the second hand will be white; by this means it will be very well
legible against the black background.

The crystal will be most likely made from plexi-plan-glass, otherwise from a strong
normal glass plate, which is completely flat.

On Wednesday, 28 August Mr. Otto Lange will be in Berlin. If it is possible, he will use
this opportunity to either visit you or talk to you on the telephone. Mr. Otto Lange will
stop at Hotel Excelsior. Perhaps the dial issue can be best resolved in a personal discussion.
Otherwise, we look forward to your written opinion, whether you agree with a non-luminescent
scale, or would prefer the inward-protruding parts of 1 - and 5-second ticks to be luminescent.

Using this opportunity, we acknowledge the receipt of the pilot watch mockup you
returned to us. It also needs to be clarified whether the size of the original pilot watch
mockup is sufficient for you, or whether the case must be reworked according to the size
indicated in your drawing.
===============================================

I looked more carefully at the photograph in the book, and indeed the inward-protruding parts
of 1- and 5-second ticks are clearly yellowish, which means they were covered with a luminous
material, whereas all the ticks in the 1/5-second part of the scale are completely white.

 

[city-dweller]

So, basically, the main issue was that the movement was hacking, and the dial was highly visible in all aspects, incl. photography.

yes.
and additionally a 1/5-second jumping second hand.
but with our movement we, of course, should forget about this feature.